Communications device, infrastructure equipment, communications system and methods

ABSTRACT

A communications device is provided, which is configured to transmit or receive signals via a wireless access interface provided by the wireless communications network to or from one or more infrastructure equipment. The communications device is configured, at the time of a Radio Resource Control (RRC) connection establishment procedure, to receive a first message from one of the infrastructure equipment comprising an indication that the infrastructure equipment is capable of operating in accordance with a packet data convergence protocol (PDCP) in accordance with a first radio access technology, to establish a PDCP entity based on the received indication, and to transmit a second message to the infrastructure equipment comprising an indication that the communications device is capable of operating in accordance with one or both of the PDCP in accordance with the first radio access technology and a PDCP in accordance with a second radio access technology.

BACKGROUND Field of Disclosure

The present disclosure relates to communications devices configured tocommunicate with infrastructure equipment of wireless communicationsnetworks, where the communications devices may be able to operate inaccordance with one or both of a Packet Data Convergence Protocol (PDCP)in accordance with a first radio access technology and a PDCP inaccordance with a second radio access technology.

The present application claims the Paris Convention priority of Europeanpatent application EP17184361.8, the contents of which are herebyincorporated by reference.

Description of Related Art

The “background” description provided herein is for the purpose ofgenerally presenting the context of the disclosure. Work of thepresently named inventors, to the extent it is described in thisbackground section, as well as aspects of the description which may nototherwise qualify as prior art at the time of filing, are neitherexpressly or impliedly admitted as prior art against the presentinvention.

Third and fourth generation mobile telecommunication systems, such asthose based on the Third Generation Project Partnership (3GPP) definedUniversal Mobile Telecommunications Standard (UMTS) and Long TermEvolution (LTE) architecture are able to support more sophisticatedservices than simple voice and messaging services offered by previousgenerations of mobile telecommunication systems. For example, with theimproved radio interface and enhanced data rates provided by LTEsystems, a user is able to enjoy high data rate applications such asmobile video streaming and mobile video conferencing that wouldpreviously only have been available via a fixed line data connection.The demand to deploy third and fourth generation networks is thereforestrong and the coverage area of these networks, i.e. geographiclocations where access to the networks is possible, is expected toincrease rapidly. However, whilst fourth generation networks can supportcommunications at high data rate and low latencies from devices such assmart phones and tablet computers, it is expected that future wirelesscommunications networks, will be expected to efficiently supportcommunications with a much wider range of devices associated with awider range of data traffic profiles, for example including reducedcomplexity devices, machine type communication devices, high resolutionvideo displays and virtual reality headsets. Some of these differenttypes of devices may be deployed in very large numbers, for example lowcomplexity devices for supporting the “The Internet of Things”, and maytypically be associated with the transmissions of relatively smallamounts of data with relatively high latency tolerance, whereas othertypes of device, for example supporting high-definition video streaming,may be associated with transmissions of relatively large amounts of datawith relatively low latency tolerance.

There is therefore expected to be a desire for future wirelesscommunications networks, which may be referred to as 5G or new radioaccess technology (which may be denoted new RAT or, simply, NR)networks, to support efficiently connectivity for a wide range ofdevices associated with different applications with differentcharacteristic data traffic profiles, resulting in different deviceshaving different operating characteristics and/or requirements.

The introduction of new radio access technology (RAT) systems/networkstherefore gives rise to new opportunities as well as challenges. Onesuch challenge is how to adapt presently used protocols and proceduressuch that they can work with both legacy (i.e. LTE) devices and NRdevices. An example of this would be a Packet Data Convergence Protocol(PDCP), which is different for NR than for LTE; an LTE UE will not beable to use NR-PDCP.

SUMMARY OF THE DISCLOSURE

The present disclosure can help address or mitigate at least some of theissues discussed above.

Embodiments of the present technique can provide a communications deviceconfigured to transmit or receive signals via a wireless accessinterface provided by the wireless communications network to or from oneor more infrastructure equipment forming part of the wirelesscommunications network, wherein the communications device is configured,during of a Radio Resource Control, RRC, connection establishmentprocedure, to receive a first message from one of the infrastructureequipment comprising an indication that the infrastructure equipment iscapable of operating in accordance with a packet data convergenceprotocol, PDCP, in accordance with a first radio access technology, toestablish a PDCP entity based on the indication received in the firstmessage, and subsequently to transmit a second message to theinfrastructure equipment comprising an indication that thecommunications device is capable of operating in accordance with one orboth of the PDCP in accordance with the first radio access technologyand a PDCP in accordance with a second radio access technology.

Embodiments of the present technique, which further relate toinfrastructure equipment, communications systems, methods of operatingcommunications devices, infrastructure equipment and communicationssystems, and circuitry for communications devices, infrastructureequipment and communications systems, allow for the configuration ofNR-PDCP for master cell group (MCG) signalling radio bearers (SRBs) whenthe MCG is LTE, where the communications devices may be either NRdevices supporting LTE-NR dual connectivity or legacy devices.

Respective aspects and features of the present disclosure are defined inthe appended claims.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary, but are notrestrictive, of the present technology. The described embodiments,together with further advantages, will be best understood by referenceto the following detailed description taken in conjunction with theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete appreciation of the disclosure and many of the attendantadvantages thereof will be readily obtained as the same becomes betterunderstood by reference to the following detailed description whenconsidered in connection with the accompanying drawings wherein likereference numerals designate identical or corresponding parts throughoutthe several views, and wherein:

FIG. 1 is a schematic block diagram of a wireless communications systemwith architectural components corresponding to that of an exampleenhanced new radio or 5G network;

FIG. 2 is a schematic block diagram showing a UE and network supportingdual connectivity and having an LTE-PDCP entity or an NR-PDCP entity;

FIG. 3 is a first example of a message flow diagram showing a messageexchange between a communications device and an infrastructure equipmentin accordance with embodiments of the present technique;

FIG. 4 is a second example of a message flow diagram showing a messageexchange between a communications device and an infrastructure equipmentin accordance with embodiments of the present technique;

FIG. 5 illustrates the changes required in MSG4 of a RACH procedure inconsideration of some embodiments of the present technique;

FIG. 6 illustrates the changes required in MSG5 of a RACH procedure inconsideration of some embodiments of the present technique;

FIG. 7 illustrates the format of the PDCP Data Protocol Data Unit (PDU)for SRBs;

FIG. 8 is a third example of a message flow diagram of an example ofmessage exchange between a communications device and an infrastructureequipment in accordance with embodiments of the present technique;

FIG. 9 shows a first flow diagram illustrating a process ofcommunications in a communications system in accordance with embodimentsof the present technique; and

FIG. 10 shows a second flow diagram illustrating a process ofcommunications in a communications system in accordance with embodimentsof the present technique.

DETAILED DESCRIPTION OF THE EMBODIMENTS New Radio Access Technology (5G)

As mentioned above, the embodiments of the present invention can findapplication with advanced wireless communications systems such as thosereferred to as 5G or New Radio (NR) Access Technology. It has beenproposed to develop a new Radio Access Technology (RAT) for the nextgeneration wireless communication system, i.e. 5G, and in 3GPP a StudyItem (SI) on NR has been agreed [1] in order to study and develop thenew RAT. The new RAT is expected to operate in a large range offrequencies, from hundreds of MHz to 100 GHz and it is expected to covera broad range of use cases. The use cases that are considered under thisSI include:

-   -   Enhanced Mobile Broadband (eMBB)    -   Massive Machine Type Communications (mMTC)    -   Ultra Reliable & Low Latency Communications (URLLC)

The aim of 5G is not only mobile connectivity for people, but to provideubiquitous connectivity for any type of device and any type ofapplication that would benefit from being connected. Many requirementsand use-cases are still being discussed, but amongst those are:

-   -   Low latency    -   High data rates    -   Millimetre wave spectrum use    -   High density of network nodes (e.g. small cell and relay nodes)    -   Large system capacity    -   Large numbers of devices (e.g. MTC devices/Internet of Things        devices)    -   High reliability (e.g. for vehicle safety applications, such as        self-driving cars)    -   Low device cost and energy consumption    -   Flexible spectrum usage    -   Flexible mobility

An example configuration of a wireless communications network which usessome of the terminology proposed for NR and 5G is shown in FIG. 1. InFIG. 1 a plurality of transmission and reception points (TRP) 10 areconnected to distributed control units (DU) 11.1, 11.2 by a connectioninterface represented as a line 3. Each of the transmitter receiverpoints (TRP) 10 is arranged to transmit and receive signals via awireless access interface within a radio frequency bandwidth availableto the wireless communications network. Thus within a range forperforming radio communications via the wireless access interface, eachof the TRP 10, forms a cell of the wireless communications network asrepresented by a dashed line 8. As such wireless communications devices12 which are within a radio communications range provided by the cells10 can transmit and receive signals to and from the TRP 10 via thewireless access interface. Each of the distributed control units 11.1,11.2 are connected to a co-ordinating unit (CU) 14 via an interface 16.The CU 14 is then connected to the a core network 17 which may containall other functions required for communicating data to and from thewireless communications devices and the core network 17 may be connectedto other networks 18.

The elements of the wireless access network shown in FIG. 1 may operatein a similar way to corresponding elements of an LTE network well-knownand defined in the relevant standards administered by the 3GPP (RTM)body, and also described in many books on the subject, for example,Holma H. and Toskala A [2]. It will be appreciated that operationalaspects of the telecommunications network represented in FIG. 1, and ofother networks discussed herein in accordance with embodiments of thedisclosure, which are not specifically described (for example inrelation to specific communication protocols and physical channels forcommunicating between different elements) may be implemented inaccordance with any known techniques, for example according to currentlyused approaches for implementing such operational aspects of wirelesstelecommunications systems, e.g. in accordance with the relevantstandards.

The transceiver processors TRP 10 of FIG. 1 may in part have acorresponding functionality to a base station or eNodeB of an LTEnetwork, and so the terms TRP and eNodeB in the following descriptionare interchangeable. Base stations, which are an example of radionetwork infrastructure equipment, may also be referred to as transceiverstations/NodeBs/eNodeBs (eNBs)/gNodeBs (gNBs), and so forth. Similarlythe communications devices 12 may have a functionality corresponding todevices know for operation with an LTE network and may also be referredto as mobile stations, user equipment (UE), user terminal, terminaldevice, mobile radio, communications device, and so forth. It will beappreciated therefore that operational aspects of a new RAT network (forexample in relation to specific communication protocols and physicalchannels for communicating between different elements) may be differentto those known from LTE or other known mobile telecommunicationsstandards. However, it will also be appreciated that each of the corenetwork component, base stations and terminal devices of a new RATnetwork will be functionally similar to, respectively, the core networkcomponent, base stations and terminal devices of an LTE wirelesscommunications network.

At least for initial deployment, NR and LTE are expected to coexist. InNR, there are in general two operational modes. These are a tightinterworking mode and standalone mode. In tight interworking mode, an NReNodeB works together with an LTE eNodeB. This may occur using anapproach similar to, for example, dual connectivity (as known in LTE),and may include, for example, the LTE eNodeB working as an anchor eNodeBfor the 5G NR eNodeB. On the other hand, in standalone mode, an NReNodeB could work independently without the assistance of an LTE eNodeB.The Packet Data Convergence Protocol (PDCP) operates differently in NRand LTE, and so for LTE-NR dual connectivity deployments, when UEs maycapable of operating in accordance with either NR or LTE, it isnecessary to determine what capability the UEs have, and thereforewhether to use NR-PDCP or LTE-PDCP at a time of Radio Resource Control(RRC) connection establishment.

PDCP Entities for MCG Bearer

Some appreciation of the packet data convergence protocol (PDCP) can begarnered from many sources, such as [3]. The PDCP layer runs on top ofthe radio resource control (RLC) layer, and the Medium Access Control(MAC) layer. A PDCP is used to perform the PDCP functions, and this canbe configured either with both a transmitting and a receiving side (fora bidirectional radio bearer), or only one of a transmitting and areceiving side (for a unidirectional radio bearer). Radio bearersutilizing PDCP entities can be categorized into Signalling Radio Bearer(SRB) and Data Radio Bearers (DRBs), where the DRBs can be either, RLCAcknowledged Mode (AM), which includes Automatic Repeat Request (ARQ)for error-free packet delivery or RLC Unacknowledged Mode (UM), whereretransmission is not necessary. The PDCP control unit manages controlinformation generated by the PDCP entity. Two kinds of controlinformation are defined: PDCP status report and Robust HeaderCompression (ROHC) feedback. The PDCP entity performs headercompression, security functions, handover support functions, maintenanceof PDCP sequence numbers for SRB and DRB and timer-based SDU discard forSRB and DRB.

There was a discussion during a 3GPP meeting documented in [4] on whichPDCP entity should be configured for master cell group (MCG)-SRBs. Itwas already agreed that the UE and the network will use NR-PDCP for MCGsplit bearers, secondary cell group (SCG) bearers and SCG split bearersif the UE/network support dual connectivity between LTE and NR. If theUE uses NR-PDCP for MCG-SRBs as well, then there is no need to maintaintwo PDCP entity types (i.e. both LTE-PDCP and NR-PDCP) in the UE andnetwork for the UE and network supporting dual connectivity, as shown inFIG. 2. It is possible to use NR-PDCP for DRBs anchored in the LTE MCG,as also shown in FIG. 2.

In [4], it was agreed that the PDCP configuration should be includedwithin the NR RRC PDU from the secondary node to allow direct SCG SRBreconfiguration of PDCP, and that it was assumed that the SRB or DRB IDis used from the linking. It was also agreed that either LTE or NR PDCPcould be used, and that this would be configurable by the network. Noclear consensus was reached however, and no concrete solutions wereproposed. The following points in [4], labelled as those for furtherstudy, are addressed by embodiments of the present technique:

-   -   Which PDCP should be used for MCG SRB at the time of connection        setup?    -   What mechanism is used (if needed) to indicate to the network        whether or not the UE supports NR-PDCP during connection setup?    -   Whether to support a mechanism to reconfigure from LTE-PDCP to        NR-PDCP without handover, and if so, what would this mechanism        look like?

If the first and second of the above points are resolved, and NR-PDCP isalways configured for MCG SRB, then reconfiguration without handover maynot be needed. To start with, it is good to know the difference betweenLTE-PDCP and NR-PDCP for the configuration of SRB1, which is that LTEuses PDCP sequence number (SN) based reception mechanism, whereasNR-PDCP will use COUNT instead of PDCP SN. COUNT comprises PDCP SN, sofrom a functional point of view, NR-PDCP also takes the Hyper FrameNumber (HFN) value, which is a number which is incremented each time thePDCP SN wraps around, into account in addition to the PDCP SN. This isthe main difference between LTE PDCP and NR-PDCP in the context of SRB1.

LTE SRB handling, and the assumed NR SRB handling is described below,with some wording being taken from the 3GPP Technical Specification36.323 [3]:

For SRBs, at reception of a PDCP Data PDU from lower layers, the UEshall:

-   -   If received PDCP SN<Next_PDCP_RX_SN:        -   decipher and verify the integrity of the PDU (if applicable)            using COUNT based on RX_HFN+1 and the received PDCP SN as            specified in the subclauses 5.6 and 5.7, respectively;    -   else:        -   decipher and verify the integrity of the PDU (if applicable)            using COUNT based on RX_HFN and the received PDCP SN as            specified in the subclauses 5.6 and 5.7, respectively;    -   if integrity verification is applicable and the integrity        verification is passed successfully; or    -   if integrity verification is not applicable:        -   if received PDCP SN<Next_PDCP_RX_SN:            -   increment RX_HFN by one;        -   set Next_PDCP_RX_SN to the received PDCP SN+1;        -   if Next_PDCP_RX_SN>Maximum PDCP SN:            -   set Next_PDCP_RX_SN to 0;            -   increment RX_HFN by one;        -   deliver the resulting PDCP SDU to upper layer;    -   else, if integrity verification is applicable and the integrity        verification fails:        -   discard the received PDCP Data PDU;        -   indicate the integrity verification failure to upper layer.

At reception of a PDCP Data PDU from lower layers, the receiving PDCPentity shall determine the COUNT value of the received PDCP PDU, i.e.RCVD_COUNT, as follows:

-   -   if RCVD_SN<=SN(RX_DELIV)−Window_Size:        -   RCVD_HFN=HFN(RX_DELIV)+1;    -   else if RCVD_SN>SN(RX_DELIV)+Window_Size:        -   RCVD_HFN=HFN(RX_DELIV)−1;    -   else:        -   RCVD_HFN=HFN(RX_DELIV);    -   RCVD_COUNT=[RCVD_HFN, RCVD_SN].

After determining the COUNT value of the received PDCP PDU=RCVD_COUNT,the receiving PDCP entity shall:

-   -   if RCVD_COUNT<=RX_DELIV; or    -   if the PDCP PDU with COUNT=RCVD_COUNT has been received before:        -   perform deciphering and integrity verification of the PDCP            PDU using COUNT=RCVD_COUNT, if applicable;        -   if integrity verification fails:            -   indicate the integrity verification failure to upper                layer;        -   discard the PDCP PDU;    -   else:        -   perform deciphering and integrity verification of the PDCP            PDU using COUNT=RCVD_COUNT, if applicable;        -   if integrity verification fails:            -   indicate the integrity verification failure to upper                layer;            -   discard the PDCP PDU;

If the received PDCP PDU with COUNT value=RCVD_COUNT is not discardedabove, the receiving PDCP entity shall:

-   -   store the resulting PDCP SDU in the reception buffer;    -   if RCVD_COUNT>=RXNEXT:        -   update RX_NEXT to RCVD_COUNT+1;    -   if RCVD_COUNT=RX_DELIV+1:        -   deliver to upper layers in ascending order of the associated            COUNT value after performing header decompression, if            configured;            -   all stored PDCP SDU(s) with consecutively associated                COUNT value(s) starting from COUNT=RX_DELIV+1;        -   update RX_DELIV to the COUNT value of the last PDCP SDU            delivered to upper layers;    -   if t-Reordering is running, and if the PDCP SDU with        COUNT=RX_REORD−1 has been delivered to upper layers:        -   stop and reset t-Reordering;    -   if t-Reordering is not running (includes the case when        t-Reordering is stopped due to actions above), and if there is        at least one stored PDCP SDU:        -   update RX_REORD to RX_NEXT;        -   start t-Reordering.

Some other differences between LTE and NR-PDCP are described below. Theintention is to establish what different handling is required if NR-PDCPis used instead of LTE-PDCP, and at what stage the network and UE muststart using NR-PDCP, if NR-PDCP is selected for SRB:

-   -   Packet duplication when a split SRB is configured. Most likely,        a split SRB is not configured in MSG4 (of a RACH procedure) even        if the bearer is offloaded during initial context setup. The        assumption is that a split SRB is configured at the same time as        the bearer is offloaded. However, there is a possibility that        MSG4 configures a split SRB, because bearer offloading will also        be done blindly. So, split SRB1 configuration can be provided in        MSG4, if security is not a concern. If security is concern        however, then this won't happen before the first reconfiguration        message;    -   Jumbo frames—a size of 9 KB may be applicable to SRB1. However,        though the RRC message size may not be this big initially, this        is something which may happen in the future;    -   Pre-processing—this is not applicable to SRB1, as SRB data needs        to be transmitted with a high priority;    -   LTE-PDCP RLC-UM uses a PULL window whereas NR-PDCP RLC-UM will        use a PUSH window for all. However, RLC-UM is not used for SRB.

It is necessary to determine at what stage the network configures a UEto use NR-PDCP for MCG-SRB. It may be the case that either the UE ornetwork, or both the UE and the network, do not support MCG SRB onNR-PDCP. In such a case, unnecessary switching between LTE-PDCP andNR-PDCP should be avoided. Embodiments of the present technique seek toresolve this problem.

Configuration of NR-PDCP for MCG SRB1

No PDCP entity is used for the transmission/reception of MSG1, 2, 3 and4. The earliest possibility at which a UE can be configured to useNR-PDCP is during MSG4 (transmitted on the downlink). UE capabilityinformation is needed before MSG4, and there has already been a proposalin [4] for MSG3 to include UE NR-PDCP capability. One drawback of usingMSG3 for this purpose is that there is only one spare bit left in MSG3,and so MSG3 should not be used for this purpose if an alternativesolution is found.

FIG. 3 illustrates one such solution. FIG. 3 is a message flow diagramshowing a message exchange between a communications device 12 and aninfrastructure equipment 10 in accordance with embodiments of thepresent technique. The communications device 12 is configured totransmit or receive signals via a wireless access interface provided bya wireless communications network to or from one or more infrastructureequipment 10 forming part of the wireless communications network,wherein the communications device 12 is configured, at the time of aRadio Resource Control, RRC, connection establishment procedure, toreceive 30 a first message from one of the infrastructure equipment 10comprising an indication that the infrastructure equipment 10 is capableof operating in accordance with a packet data convergence protocol,PDCP, in accordance with a first radio access technology, to establish32 a PDCP entity based on the indication received in the first message,and subsequently to transmit 34 a second message to the infrastructureequipment 10 comprising an indication that the communications device 12is capable of operating in accordance with one or both of the PDCP inaccordance with the first radio access technology and a PDCP inaccordance with a second radio access technology.

In some embodiments, the second message is transmitted by thecommunications device using the PDCP entity that it established based onthe indication received in the first message.

FIG. 4 is a message flow diagram showing a message exchange between acommunications device 12 and an infrastructure equipment 10 inaccordance with embodiments of the present technique. FIG. 4 issubstantially equivalent to FIG. 3, but demonstrates the process fromthe viewpoint of the network. The infrastructure equipment 10, whichforms part of the wireless communications network, is configured totransmit or receive signals via a wireless access interface provided bythe wireless communications network to or from one or morecommunications devices 12, wherein the infrastructure equipment 10 isconfigured, at the time of a Radio Resource Control, RRC, connectionestablishment procedure, to transmit 40 a first message to one of thecommunications devices 12 comprising an indication that theinfrastructure equipment 10 is capable of operating in accordance with apacket data convergence protocol, PDCP, in accordance with a first radioaccess technology, to receive 42 a second message from thecommunications device 12 comprising an indication that thecommunications device 12 is capable of operating in accordance with oneor both of the PDCP in accordance with the first radio access technologyand a PDCP in accordance with a second radio access technology, and toselect 44 the PDCP in accordance with the first radio access technologyfor future communications with the communications device 12 if thecommunications device 12 is capable of operating in accordance with thePDCP in accordance with the first radio access technology, or else toselect the PDCP in accordance with the second radio access technologyfor future communications with the communications device 12.

In some embodiments relating to FIGS. 3 and 4, the first message formspart of a random access procedure between the communications device andthe infrastructure equipment. In some embodiments relating to FIGS. 3and 4, the first radio access technology is New Radio (NR), and/or thesecond radio access technology is Long Term Evolution (LTE).

Such solutions as illustrated in FIGS. 3 and 4 constitute blindactivation without the network knowing the UE's capability of NR-PDCP inMSG4. If the UE does not understand the Non Critical Extension inAbstract Syntax Notation 1 (ASN.1), then it will continue using LTE-PDCPin MSG5. Example changes to MSG4 are shown in FIG. 5 (the text writtenin darker font), whereby a new “SRB to Add” information element (IE) isincluded (RadioResourceConfigDedicated). Legacy UEs will ignore this IE,and UEs capable of E-UTRA-NR Dual Connectivity (EN-DC) will configureNR-PDCP for SRB1.

Alternatively to transmitting it in the first message as defined byFIGS. 3 and 4, the network's capability to support NR-PDCP may bebroadcast. Therefore, in some embodiments, the first message is receivedfrom the infrastructure equipment as a broadcast. In general, thebroadcast of network capability is not a particularly nice solution, but3GPP is investigating whether an eNodeB can broadcast, in an LTE cell,the capability to perform LTE-NR dual connectivity. This use case isrelated to service indication, like the High-Speed Packet Access (HSPA)indicator in UTRA, but it can be used as an indication showing networkcapability. The network must then be prepared to receive MSG5 both onLTE-PDCP and on NR-PDCP.

In some embodiments, MSG1 or MSG3 resource allocation is differentcompared to legacy UEs. This will result in duplicate resourceallocation for a UE, assuming it will pick one of these allocatedresources based on its PDCP capability. In other words, thecommunications device is configured to receive an indication of a firstset of communications resources from one of the infrastructure equipmentand to receive an indication of a second set of communications resourcesfrom the infrastructure equipment, and to transmit signals comprisingdata to the infrastructure equipment in the first set of communicationsresources if the communications device is capable of operating inaccordance with the PDCP in accordance with the first radio accesstechnology and to transmit signals comprising data to the infrastructureequipment in the second set of communications resources if thecommunications device is not capable of operating in accordance with thePDCP in accordance with the first radio access technology.

In such embodiments described above, the UE behaviour for MSG5 islargely the same, i.e. the UE will use NR-PDCP for MSG5 if it is capableof doing so, and has successfully decoded MSG4 or the broadcast or anyother alternative in which the network indicated its own capability ofusing NR-PDCP. RRC MSG5 will include the UE's capability or support forNR-PDCP, and the network may decode MSG5 using either NR-PDCP orLTE-PDCP because the HFN part (which as described above is the maindifference between NR-PDCP and LTE-PDCP) may not be necessary to receiveMSG5 in NR-PDCP and so therefore the operation of NR-PDCP is essentiallythe same as for LTE-PDCP in terms of MSG5 reception. HFNdesynchronization is not a problem when PDCP SN has just beeninitialised. On reception of this message and a new IE, the network willchange the configuration of PDCP, if required. The changes to MSG5 areshown in FIG. 6.

As described above, in some embodiments, the indication transmitted inthe second message is comprised within an RRC IE of the second message.However, alternatively, embodiments of the present technique may use anew bit in the PDCP header to indicate that the NR-PDCP protocol hasbeen used. This will avoid reconfiguration on the network side asdescribed above. For this purpose, the reserved (R) bit can be used. TheLTE-PDCP layer does not look into the R bit, and it always assumed to beset to “0”. If the UE supports NR-PDCP then, in one of the embodiments,the R bit in NR-PDCP header is set to “1”.

FIG. 7 illustrates the format of the PDCP Data Protocol Data Unit (PDU),with 12 bits PDCP SN, which is applicable for SRBs. Here, the R bits 72can be seen, and in LTE-PDCP as described above, is set to “0” and thesereserved bits will be ignored by the receiver. The intention is thesecond bit is used instead of the first bit in order to avoid confusionwith the DRB PDU. So, the network side PDCP, while receiving MSG5, willneed to check if the R bit has been set to “1” and then decide on thatbasis which PDCP entity to choose. There could be a layer sandwichedbetween the RLC and PDCP layers on the network side which checks onlythe setting of the R bit field in the PDCP header by the UE. In theseembodiments, the network always allocates NR-PDCP to the UE. If the Rbit is set to “0” then NR-PDCP sets up LTE-PDCP for the UE. This may bedone via RRC or via control software on the eNodeB side. In other words,the indication transmitted in the second message is comprised within aPDCP header of the second message.

Alternatively still, a new bit in the RLC header may be used, and if theNR-PDCP resides in a different location then the RLC layer needs toroute the PDCP PDU to the correct PDCP entity. In other words theindication transmitted in the second message may be comprised within aRadio Link Control (RLC) header of the second message. Further, it maybe that the indication transmitted in the second message is comprisedwithin a Medium Access Control (MAC) header of the second message.

Two MSG3 sizes have been agreed in 3GPP, and RA partitioningcorresponding to each MSG3 size for NR is needed. According to someembodiments of the present technique, one of the MSG3 sizes is linked tothe support of NR-PDCP and is based on RA partition. This is related tothe embodiment described above in which a new bit in the RLC header isused to indicate whether or not the network is capable of using NR-PDCP.In some further embodiments, one of the MSG3 sizes being linked to thesupport of NR-PDCP may be used in conjunction with the new bit in theRLC header indicating whether or not the network is capable of usingNR-PDCP.

In further embodiments of the present technique, a preamble is assignedfor initial access of UEs capable of using NR-PDCP for SRB1, so that thenetwork is aware of the UE's capability. In other words, thecommunications device is configured to determine that the communicationsdevice should transmit data to the wireless communications network, andto transmit an initial access signal to one of the infrastructureequipment, wherein a preamble of the initial access signal comprises anindication that the communications device is capable of operating inaccordance with one or both of the PDCP in accordance with the firstradio access technology and the PDCP in accordance with the second radioaccess technology.

FIG. 8 shows an overview of the present technique, encompassing at leastsome of the embodiments of the present technique as described above,implemented in a communications system comprising a communicationsdevice (UE) 12 and an infrastructure equipment (eNodeB) 10. Each of theUE 12 and the eNB 10 comprise an RRC layer 820, 800, an LTE-PDCP layer822, 802, an NR-PDCP layer 824, 804, an RLC layer 826, 806 and a MAClayer 828, 808. A MSG3 transmission request 830 is transmitted from theRRC layer 820 to the MAC layer 828 of the UE 12. In response, a preambleresource selection 832 is carried out at the MAC layer 828, andtransmitted to the MAC layer 808 of the eNB 10 as part of MSG1 of arandom access procedure. Based on this, a Cell Radio Network TemporaryIdentifier (C-RNTI) 836 is allocated by the MAC layer 808 of the eNB 10and this is transmitted to the MAC layer 828 of the UE 12 as part ofMSG2 838. The MAC layer 828 of the UE 12 then transmits MSG3 840 to theMAC layer 808 of the eNB 10, and this is forwarded 842 to the RRC layer800 of the eNB 10, where PDCP and RLC entities are allocated 844. TheRRC layer 800 of the eNB 10 then configures both the PDCP 846 and RLC848 entities on the basis of this, and transmits MSG4 850 to the RRClayer 820 of the UE 12, which includes the NR-PDCP configuration inNon-Critical Extension. At the UE's 12 RRC layer 820, an attempt is madeto comprehend the PDCP configuration 852 based on the capability of theUE 12. If comprehended, then the UE configures the NR-PDCP entity. To doso, the RRC layer 820 of the UE 12 transmits a dedicated control channel(DCCH) 854 to the NR-PDCP layer 824 comprising MSG5. At the NR-PDCPlayer 824, the reserved (R) field may be set to “1” 856 in the PDCPheader, and MSG5 is then forwarded 858 to the RLC layer 826 andforwarded again 860 to the MAC layer 828, where it is transmitted 862 tothe MAC layer 808 of the eNB 10. The MAC layer 808 then forwards MSG5864 to the RLC layer 806, and regardless of its composition (i.e. inrelation to any indication of the UE's support of NR-PDCP), this isforwarded 866, 868 to the NR-PDCP layer 802 of the eNB 10. At theNR-PDCP layer 802, it may the case that LTE-PDCP is selected if the UEdoes not support NR-PDCP 870, but in any case, MSG5 is finally forwarded872 to the RRC layer 800 of the eNB 10.

FIG. 9 shows a first flow diagram illustrating a process ofcommunications in a communications system in accordance with embodimentsof the present technique. The method, which is a method of operating acommunications device configured to transmit or receive signals via awireless access interface provided by a wireless communications networkto or from one or more infrastructure equipment forming part of thewireless communications network, begins in step S90. The methodcomprises, at the time of a Radio Resource Control, RRC, connectionestablishment procedure, in step S92, receiving a first message from oneof the infrastructure equipment comprising an indication that theinfrastructure equipment is capable of operating in accordance with apacket data convergence protocol, PDCP, in accordance with a first radioaccess technology. In step S94, the method comprises establishing a PDCPentity based on the indication received in the first message, andsubsequently in step S96, transmitting a second message to theinfrastructure equipment comprising an indication that thecommunications device is capable of operating in accordance with one orboth of the PDCP in accordance with the first radio access technologyand a PDCP in accordance with a second radio access technology. Theprocess ends in step S98.

FIG. 10 shows a second flow diagram illustrating a process ofcommunications in a communications system in accordance with embodimentsof the present technique. The method, which is a method of operating aninfrastructure equipment forming part of a wireless communicationsnetwork configured to transmit or receive signals via a wireless accessinterface provided by the wireless communications network to or from oneor more communications devices, begins in step S100. The methodcomprises, at the time of a Radio Resource Control, RRC, connectionestablishment procedure, in step S102, transmitting a first message toone of the communications devices comprising an indication that theinfrastructure equipment is capable of operating in accordance with apacket data convergence protocol, PDCP, in accordance with a first radioaccess technology. In step S104, the method comprises receiving a secondmessage from the communications device comprising an indication that thecommunications device is capable of operating in accordance with one orboth of the PDCP in accordance with the first radio access technologyand a PDCP in accordance with a second radio access technology, and instep S106, selecting the PDCP in accordance with the first radio accesstechnology for future communications with the communications device ifthe communications device is capable of operating in accordance with thePDCP in accordance with the first radio access technology, or elseselecting the PDCP in accordance with the second radio access technologyfor future communications with the communications device. The processends in step S98.

As described above, embodiments of the present technique allow for theconfiguration of NR-PDCP for master cell group (MCG) signalling radiobearers (SRBs), where the communications devices may be either NRdevices supporting LTE-NR dual connectivity or legacy devices.

Embodiments of the present technique also relate to infrastructureequipment and communications systems as described in the precedingparagraphs in relation to communications devices, along with methods ofoperating and circuitry for the same. Those skilled in the art wouldappreciate that such infrastructure equipment and/or communicationssystems may be further defined in accordance with the variousarrangements and embodiments discussed in the preceding paragraphs. Itwould be further appreciated by those skilled in the art that suchinfrastructure equipment and communications devices as herein definedand described may form part of communications systems other than thosedefined by the present invention.

The following numbered paragraphs provide further example aspects andfeatures of the present technique:

Paragraph 1. A communications device configured to transmit or receivesignals via a wireless access interface provided by a wirelesscommunications network to or from one or more infrastructure equipmentforming part of the wireless communications network, wherein thecommunications device is configured, at the time of a Radio ResourceControl, RRC, connection establishment procedure,

-   -   to receive a first message from one of the infrastructure        equipment comprising an indication that the infrastructure        equipment is capable of operating in accordance with a packet        data convergence protocol, PDCP, in accordance with a first        radio access technology,    -   to establish a PDCP entity based on the indication received in        the first message, and subsequently    -   to transmit a second message to the infrastructure equipment        comprising an indication that the communications device is        capable of operating in accordance with one or both of the PDCP        in accordance with the first radio access technology and a PDCP        in accordance with a second radio access technology.

Paragraph 2. A communications device according to Paragraph 1, whereinthe second message is transmitted by the communications device using theestablished PDCP entity.

Paragraph 3. A communications device according to Paragraph 1 orParagraph 2, wherein the indication transmitted in the second message iscomprised within an RRC Information Element, IE, of the second message.

Paragraph 4. A communications device according to Paragraph 1 orParagraph 2, wherein the indication transmitted in the second message iscomprised within a PDCP header of the second message.

Paragraph 5. A communications device according to Paragraph 1 orParagraph 2, wherein the indication transmitted in the second message iscomprised within a Radio Link Control, RLC, header of the secondmessage.

Paragraph 6. A communications device according to Paragraph 1 orParagraph 2, wherein the indication transmitted in the second message iscomprised within a Medium Access Control, MAC, header of the secondmessage.

Paragraph 7. A communications device according to any of Paragraphs 1 to6, wherein the first message is received from the infrastructureequipment as a broadcast.

Paragraph 8. A communications device according to any of Paragraphs 1 to6, wherein the first message forms part of a random access procedurebetween the communications device and the infrastructure equipment.

Paragraph 9. A communications device according to any of Paragraphs 1 to8, configured

-   -   to receive an indication of a first set of communications        resources from one of the infrastructure equipment and to        receive an indication of a second set of communications        resources from the infrastructure equipment, and    -   to transmit signals comprising data to the infrastructure        equipment in the first set of communications resources if the        communications device is capable of operating in accordance with        the PDCP in accordance with the first radio access technology        and to transmit signals comprising data to the infrastructure        equipment in the second set of communications resources if the        communications device is not capable of operating in accordance        with the PDCP in accordance with the first radio access        technology.

Paragraph 10. A communications device according to any of Paragraphs 1to 9, wherein the communications device is configured to determine thatthe communications device should transmit data

-   -   to the wireless communications network, and    -   to transmit an initial access signal to one of the        infrastructure equipment, wherein a preamble of the initial        access signal comprises an indication that the communications        device is capable of operating in accordance with one or both of        the PDCP in accordance with the first radio access technology        and the PDCP in accordance with the second radio access        technology.

Paragraph 11. A communications device according to any of Paragraphs 1to 10, wherein the first radio access technology is New Radio, NR.

Paragraph 12. A communications device according to any of Paragraphs 1to 11, wherein the second radio access technology is Long TermEvolution, LTE.

Paragraph 13. An infrastructure equipment forming part of a wirelesscommunications network configured to transmit or receive signals via awireless access interface provided by the wireless communicationsnetwork to or from one or more communications devices, wherein theinfrastructure equipment is configured, at the time of a Radio ResourceControl, RRC, connection establishment procedure,

-   -   to transmit a first message to one of the communications devices        comprising an indication that the infrastructure equipment is        capable of operating in accordance with a packet data        convergence protocol, PDCP, in accordance with a first radio        access technology,    -   to receive a second message from the communications device        comprising an indication that the communications device is        capable of operating in accordance with one or both of the PDCP        in accordance with the first radio access technology and a PDCP        in accordance with a second radio access technology, and    -   to select the PDCP in accordance with the first radio access        technology for future communications with the communications        device if the communications device is capable of operating in        accordance with the PDCP in accordance with the first radio        access technology, or else to select the PDCP in accordance with        the second radio access technology for future communications        with the communications device.

Paragraph 14. An infrastructure equipment according to Paragraph 13,wherein the indication received in the second message is comprisedwithin a Radio Resource Control Information Element, RRC IE, of thesecond message.

Paragraph 15. An infrastructure equipment according to Paragraph 13,wherein the indication received in the second message is comprisedwithin a PDCP header of the second message.

Paragraph 16. An infrastructure equipment according to Paragraph 13,wherein the indication received in the second message is comprisedwithin a Radio Link Control, RLC, header of the second message.

Paragraph 17. An infrastructure equipment according to Paragraph 13,wherein the indication received in the second message is comprisedwithin a Medium Access Control, MAC, header of the second message.

Paragraph 18. An infrastructure equipment according to any of Paragraphs13 to 17, wherein the infrastructure equipment is configured to transmitthe first message as a broadcast.

Paragraph 19. An infrastructure equipment according to any of Paragraphs13 to 17, wherein the first message forms part of a random accessprocedure between the communications device and the infrastructureequipment.

Paragraph 20. An infrastructure equipment according to any of Paragraphs13 to 19, configured

-   -   to transmit an indication of a first set of communications        Paragraphs to one of the communications devices and to transmit        an indication of a second set of communications resources to the        communications device, and    -   to receive signals comprising data from the communications        device in the first set of communications resources if the        communications device is capable of operating in accordance with        the PDCP in accordance with the first radio access technology        and to receive signals comprising data from the communications        device in the second set of communications resources if the        communications device is not capable of operating in accordance        with the PDCP in accordance with the first radio access        technology.

Paragraph 21. A communications system, comprising

-   -   one or more infrastructure equipment forming part of a wireless        communications network, and    -   a communications device configured to transmit or receive        signals via a wireless access interface provided by the wireless        communications network to or from the one or more infrastructure        equipment,    -   wherein the communications device is configured, at the time of        a Radio Resource Control, RRC, connection establishment        procedure,    -   to receive a first message from one of the infrastructure        equipment comprising an indication that the infrastructure        equipment is capable of operating in accordance with a packet        data convergence protocol, PDCP, in accordance with a first        radio access technology,    -   to establish a PDCP entity based on the indication received in        the first message, and subsequently to transmit a second message        to the infrastructure equipment comprising an indication that        the communications device is capable of operating in accordance        with one or both of the PDCP in accordance with the first radio        access technology and a PDCP in accordance with a second radio        access technology.

Paragraph 22. A method of operating a communications device configuredto transmit or receive signals via a wireless access interface providedby a wireless communications network to or from one or moreinfrastructure equipment forming part of the wireless communicationsnetwork, wherein the method comprises, at the time of a Radio ResourceControl, RRC, connection establishment procedure,

-   -   receiving a first message from one of the infrastructure        equipment comprising an indication that the infrastructure        equipment is capable of operating in accordance with a packet        data convergence protocol, PDCP, in accordance with a first        radio access technology, establishing a PDCP entity based on the        indication received in the first message, and subsequently    -   transmitting a second message to the infrastructure equipment        comprising an indication that the communications device is        capable of operating in accordance with one or both of the PDCP        in accordance with the first radio access technology and a PDCP        in accordance with a second radio access technology.

Paragraph 23. A method of operating an infrastructure equipment formingpart of a wireless communications network configured to transmit orreceive signals via a wireless access interface provided by the wirelesscommunications network to or from one or more communications devices,wherein the method comprises, at the time of a Radio Resource Control,RRC, connection establishment procedure,

-   -   transmitting a first message to one of the communications        devices comprising an indication that the infrastructure        equipment is capable of operating in accordance with a packet        data convergence protocol, PDCP, in accordance with a first        radio access technology,    -   receiving a second message from the communications device        comprising an indication that the communications device is        capable of operating in accordance with one or both of the PDCP        in accordance with the first radio access technology and a PDCP        in accordance with a second radio access technology, and    -   selecting the PDCP in accordance with the first radio access        technology for future communications with the communications        device if the communications device is capable of operating in        accordance with the PDCP in accordance with the first radio        access technology, or else selecting the PDCP in accordance with        the second radio access technology for future communications        with the communications device.

Paragraph 24. A method of operating a communications system, comprising

-   -   one or more infrastructure equipment forming part of a wireless        communications network, and    -   a communications device configured to transmit or receive        signals via a wireless access interface provided by the wireless        communications network to or from the one or more infrastructure        equipment,    -   wherein the method comprises, at the time of a Radio Resource        Control, RRC, connection establishment procedure,    -   to receive a first message from one of the infrastructure        equipment comprising an indication that the infrastructure        equipment is capable of operating in accordance with a packet        data convergence protocol, PDCP, in accordance with a first        radio access technology,    -   to establish a PDCP entity based on the indication received in        the first message, and subsequently    -   to transmit a second message to the infrastructure equipment        comprising an indication that the communications device is        capable of operating in accordance with one or both of the PDCP        in accordance with the first radio access technology and a PDCP        in accordance with a second radio access technology.

Paragraph 25. Circuitry for a communications device configured totransmit or receive signals via a wireless access interface provided bya wireless communications network to or from one or more infrastructureequipment forming part of the wireless communications network, whereinthe communications device is configured, at the time of a Radio ResourceControl, RRC, connection establishment procedure,

-   -   receiving a first message from one of the infrastructure        equipment comprising an indication that the infrastructure        equipment is capable of operating in accordance with a packet        data convergence protocol, PDCP, in accordance with a first        radio access technology,    -   establishing a PDCP entity based on the indication received in        the first message, and    -   subsequently transmitting a second message to the infrastructure        equipment comprising an indication that the communications        device is capable of operating in accordance with one or both of        the PDCP in accordance with the first radio access technology        and a PDCP in accordance with a second radio access technology.

Paragraph 26. Circuitry for an infrastructure equipment forming part ofa wireless communications network configured to transmit or receivesignals via a wireless access interface provided by the wirelesscommunications network to or from one or more communications devices,wherein the infrastructure equipment is configured, at the time of aRadio Resource Control, RRC, connection establishment procedure,

-   -   to transmit a first message to one of the communications devices        comprising an indication that the infrastructure equipment is        capable of operating in accordance with a packet data        convergence protocol, PDCP, in accordance with a first radio        access technology,    -   to receive a second message from the communications device        comprising an indication that the communications device is        capable of operating in accordance with one or both of the PDCP        in accordance with the first radio access technology and a PDCP        in accordance with a second radio access technology, and    -   to select the PDCP in accordance with the first radio access        technology for future communications with the communications        device if the communications device is capable of operating in        accordance with the PDCP in accordance with the first radio        access technology, or else to select the PDCP in accordance with        the second radio access technology for future communications        with the communications device.

Paragraph 27. Circuitry for a communications system, comprising

-   -   one or more infrastructure equipment forming part of a wireless        communications network, and    -   a communications device configured to transmit or receive        signals via a wireless access interface provided by the wireless        communications network to or from the one or more infrastructure        equipment,    -   wherein the communications device is configured, at the time of        a Radio Resource Control, RRC, connection establishment        procedure,    -   to receive a first message from one of the infrastructure        equipment comprising an indication that the infrastructure        equipment is capable of operating in accordance with a packet        data convergence protocol, PDCP, in accordance with a first        radio access technology,    -   to establish a PDCP entity based on the indication received in        the first message, and subsequently to transmit a second message        to the infrastructure equipment comprising an indication that        the communications device is capable of operating in accordance        with one or both of the PDCP in accordance with the first radio        access technology and a PDCP in accordance with a second radio        access technology.

Numerous modifications and variations of the present disclosure arepossible in light of the above teachings. It is therefore to beunderstood that within the scope of the appended claims, the disclosuremay be practiced otherwise than as specifically described herein.

In so far as embodiments of the disclosure have been described as beingimplemented, at least in part, by software-controlled data processingapparatus, it will be appreciated that a non-transitory machine-readablemedium carrying such software, such as an optical disk, a magnetic disk,semiconductor memory or the like, is also considered to represent anembodiment of the present disclosure.

It will be appreciated that the above description for clarity hasdescribed embodiments with reference to different functional units,circuitry and/or processors. However, it will be apparent that anysuitable distribution of functionality between different functionalunits, circuitry and/or processors may be used without detracting fromthe embodiments.

Described embodiments may be implemented in any suitable form includinghardware, software, firmware or any combination of these. Describedembodiments may optionally be implemented at least partly as computersoftware running on one or more data processors and/or digital signalprocessors. The elements and components of any embodiment may bephysically, functionally and logically implemented in any suitable way.Indeed the functionality may be implemented in a single unit, in aplurality of units or as part of other functional units. As such, thedisclosed embodiments may be implemented in a single unit or may bephysically and functionally distributed between different units,circuitry and/or processors.

Although the present disclosure has been described in connection withsome embodiments, it is not intended to be limited to the specific formset forth herein. Additionally, although a feature may appear to bedescribed in connection with particular embodiments, one skilled in theart would recognise that various features of the described embodimentsmay be combined in any manner suitable to implement the technique.

REFERENCES

-   [1] RP-160671, “New SID Proposal: Study on New Radio Access    Technology,” NTT DOCOMO, RAN#71.-   [2] LTE for UMTS: OFDMA and SC-FDMA Based Radio Access, Harris Holma    and Antti Toskala, Wiley 2009, ISBN 978-0-470-99401-6.-   [3] 3GPP TS 36.323, “Evolved Universal Terrestrial Radio Access    (E-UTRA); Packet Data Convergence Protocol (PDCP) specification,”    3^(th) Generation Partnership Project.-   [4] R2-1707487, “Offline discussion #3 on harmonized bearer type,”    Intel Corporation, Qingdao, China.

1. A communications device configured to transmit or receive signals viaa wireless access interface provided by a wireless communicationsnetwork to or from one or more infrastructure equipment forming part ofthe wireless communications network, wherein the communications deviceis configured, at the time of a Radio Resource Control, RRC, connectionestablishment procedure, to receive a first message from one of theinfrastructure equipment comprising an indication that theinfrastructure equipment is capable of operating in accordance with apacket data convergence protocol, PDCP, in accordance with a first radioaccess technology, to establish a PDCP entity based on the indicationreceived in the first message, and subsequently to transmit a secondmessage to the infrastructure equipment comprising an indication thatthe communications device is capable of operating in accordance with oneor both of the PDCP in accordance with the first radio access technologyand a PDCP in accordance with a second radio access technology.
 2. Acommunications device according to claim 1, wherein the second messageis transmitted by the communications device using the established PDCPentity.
 3. A communications device according to claim 1, wherein theindication transmitted in the second message is comprised within an RRCInformation Element, IE, of the second message.
 4. A communicationsdevice according to claim 1, wherein the indication transmitted in thesecond message is comprised within a PDCP header of the second message.5. A communications device according to claim 1, wherein the indicationtransmitted in the second message is comprised within a Radio LinkControl, RLC, header of the second message.
 6. A communications deviceaccording to claim 1, wherein the indication transmitted in the secondmessage is comprised within a Medium Access Control, MAC, header of thesecond message.
 7. A communications device according to claim 1, whereinthe first message is received from the infrastructure equipment as abroadcast.
 8. A communications device according to claim 1, wherein thefirst message forms part of a random access procedure between thecommunications device and the infrastructure equipment.
 9. Acommunications device according to claim 1, configured to receive anindication of a first set of communications resources from one of theinfrastructure equipment and to receive an indication of a second set ofcommunications resources from the infrastructure equipment, and totransmit signals comprising data to the infrastructure equipment in thefirst set of communications resources if the communications device iscapable of operating in accordance with the PDCP in accordance with thefirst radio access technology and to transmit signals comprising data tothe infrastructure equipment in the second set of communicationsresources if the communications device is not capable of operating inaccordance with the PDCP in accordance with the first radio accesstechnology.
 10. A communications device according to claim 1, whereinthe communications device is configured to determine that thecommunications device should transmit data to the wirelesscommunications network, and to transmit an initial access signal to oneof the infrastructure equipment, wherein a preamble of the initialaccess signal comprises an indication that the communications device iscapable of operating in accordance with one or both of the PDCP inaccordance with the first radio access technology and the PDCP inaccordance with the second radio access technology.
 11. A communicationsdevice according to claim 1, wherein the first radio access technologyis New Radio, NR.
 12. A communications device according to claim 1,wherein the second radio access technology is Long Term Evolution, LTE.13. An infrastructure equipment forming part of a wirelesscommunications network configured to transmit or receive signals via awireless access interface provided by the wireless communicationsnetwork to or from one or more communications devices, wherein theinfrastructure equipment is configured, at the time of a Radio ResourceControl, RRC, connection establishment procedure, to transmit a firstmessage to one of the communications devices comprising an indicationthat the infrastructure equipment is capable of operating in accordancewith a packet data convergence protocol, PDCP, in accordance with afirst radio access technology, to receive a second message from thecommunications device comprising an indication that the communicationsdevice is capable of operating in accordance with one or both of thePDCP in accordance with the first radio access technology and a PDCP inaccordance with a second radio access technology, and to select the PDCPin accordance with the first radio access technology for futurecommunications with the communications device if the communicationsdevice is capable of operating in accordance with the PDCP in accordancewith the first radio access technology, or else to select the PDCP inaccordance with the second radio access technology for futurecommunications with the communications device.
 14. An infrastructureequipment according to claim 13, wherein the indication received in thesecond message is comprised within a Radio Resource Control InformationElement, RRC IE, of the second message.
 15. An infrastructure equipmentaccording to claim 13, wherein the indication received in the secondmessage is comprised within a PDCP header of the second message.
 16. Aninfrastructure equipment according to claim 13, wherein the indicationreceived in the second message is comprised within a Radio Link Control,RLC, header of the second message.
 17. An infrastructure equipmentaccording to claim 13, wherein the indication received in the secondmessage is comprised within a Medium Access Control, MAC, header of thesecond message.
 18. An infrastructure equipment according to claim 13,wherein the infrastructure equipment is configured to transmit the firstmessage as a broadcast.
 19. An infrastructure equipment according toclaim 13, wherein the first message forms part of a random accessprocedure between the communications device and the infrastructureequipment.
 20. An infrastructure equipment according to claim 13,configured to transmit an indication of a first set of communicationsresources to one of the communications devices and to transmit anindication of a second set of communications resources to thecommunications device, and to receive signals comprising data from thecommunications device in the first set of communications resources ifthe communications device is capable of operating in accordance with thePDCP in accordance with the first radio access technology and to receivesignals comprising data from the communications device in the second setof communications resources if the communications device is not capableof operating in accordance with the PDCP in accordance with the firstradio access technology. 21.-27. (canceled)